molten magnesium will dissolve --nickel  use graphite crucible

Because of extremely adverse effect of Ni on the corrosion resistance on Mg, it is advisable to have only 0.1% of Ni in crucible made from steel having less than 0.12% of carbon. Molten Mg( if flux- melting procedure is used) results in the formation of sludge with comparatively low thermal conductivity at the bottom of crucible. If this material is not periodically removed, overheating can result in this area resulting in the excessive scaling of crucible.

REF:

Magnesium and Magnesium Alloys

Edited by M. M. Avedesian, Hugh Bake[Page-57].

Thank you sir both of you

Use steel crucible, this is better than any other crucible.